The present invention relates generally to a hypodermic syringe, and more particularly to an improvement on the plunger and the needle holder of the hypodermic syringe.
For the sake of safety, the conventional hypodermic syringe comprises a hypodermic needle which can be drawn into the barrel by the plunger of the syringe after injection. However, such conventional hypodermic syringe is generally defective in design in that the needle holder is devoid of a good structural cooperation with the plunger, and that the needle holder often fails to be pulled back in by the plunger. In addition, the needle of the conventional hypodermic syringe does not meet the strict standard calling for minimum drug residue in the syringe after injection.
It is the primary objective of the present invention to provide a safety hypodermic syringe comprising a needle holder which can be drawn into the barrel by the plunger with precision.
It is another objective of the present invention to provide a safety hypodermic syringe comprising a needle holder and a plunger, which cooperate to reduce the drug residue after injection.
It is still another objective of the present invention to provide a safety hypodermic syringe with a simplified structure to engage the plunger and the needle holder of the hypodermic syringe.
The safety hypodermic syringe of the present invention comprises a barrel; a needle holder slidably disposed in a receiving hole of the barrel and provided with an insertion hole forming an inner tapered hole, a pull stop edge, a fluid transporting hole in communication with a hypodermic needle; a plunger having a rod body, a hooked connection head of a conical shape and corresponding to the inner tapered hole, two claws for retaining the pull stop edge of the needle holder, and two notches located in two sides thereof.
The plunger is capable of an intimate cooperation with the needle holder, thereby resulting in a reduction in the drug residue. The plunger is capable of drawing the needle holder into the barrel with precision after injection.